The present invention concerns protection circuitry for semiconductor high voltage drivers and the like, and particularly to circuitry for protecting such load devices from power transients which occur during the system turn-on interval as well as from abnormal power conditions which may occur during system operation.
In many high voltage driver circuits, including those using PIN diodes operating at voltages in the order of one hundred to several hundred volts, the power supply interface is extremely important in determining overall circuit performance and reliability. A circuit designer can maximize driver speed and operating efficiency if means are provided to protect the driver devices from the sudden, uncontrolled application of high voltages thereto during the power turn-on interval and from other power source abnormalities, such as the absense or sudden loss of one or more additional voltages required by the load circuitry. It is also highly desireable that such protection means have the capability of accurately controlling the turn-on voltage risetime and the maximum value of the current applied to the driver circuitry.
Accordingly, it is the objective of this invention to provide simple and reliable protection circuitry for accomplishing these ends.